1. Field of the Invention
The present invention relates to the production of shaped articles from particulates by shaping such divided materials into desired form and then heat treating same. More particularly this invention relates to the production of such shaped articles as catalyst supports, catalysts, adsorbents, ceramics, and the like, having improved mechanical properties.
2. Description of the Prior Art
Processes for the production of shaped articles from finely or coarsely divided materials, such as powders, are known to this art. They typically consist either of agglomerating the powder by granulation, pelleting, or extrusion, for example, or of molding the article after formulating a suspension or solution of the divided material, followed by drying the resulting shaped article, and subjecting it to a heat treatment to completely eliminate the water therefrom, thus producing a solid shaped article having mechanical properties suitable for the intended use thereof.
The heat treatment may be carried out at a more or less elevated temperature, depending on the article to be produced. Thus, in the production of adsorbents, catalysts or catalyst supports and, more generally, shaped articles having a high pore volume, the heat treatment consists of calcination at a temperature on the order of 600.degree. C. to prevent the vanishing of the pores (which, in the case of ceramic articles, the heat treatment consists of sintering at an elevated temperature to produce a compact and dense product).
In the known processes, additives are introduced to facilitate the shaping operation. Nonetheless, the articles obtained after the heat treatment do not have good mechanical properties.
Thus, catalysts or catalyst supports based on alumina have relatively low crush resistance (ESH) or grain-to-grain crush resistance (EGG), which may lead to fracture during the handling of the catalyst or its use.
Furthermore, catalysts supports are typically impregnated with solutions of precursors of the elements constituting the catalytically active phase. The supports produced by the known processes may rupture or burst during such impregnation. The percentage of crushing or fracturing may be high as a function of the initial powder.